1. Fields of the Invention
The present invention relates to a monitor system for monitoring riverbed elevation changes at bridge piers, especially to a monitor system that processes monitor images to get the riverbed elevation changes at bridge piers and send the riverbed elevation changes to a remote monitor unit for a real-time monitoring.
2. Descriptions of Related Art
In recent years, natural disasters such as storms and associated flooding become more frequent and severe in countries all over the world. When the disaster comes, it causes serious flooding on the rivers and other streams so that the scour of the bridge foundations is becoming worse and this leads to exposure of bridge foundations. Thus the lateral support on the bridge pier is insufficient and the bridge may be tilted or broken. Once the flooding is too vast, the pier is washed away, the bridge collapses and people passing through the bridge may fall into the water. The above condition not only results in traffic interruption, but also great damages to human lives, common property and local construction. Now in order to observe the riverbed scour at bridge piers and make an alarm, a monitor system is developed. Thus the riverbed scour at bridge piers can be found as early as possible so as to assure the bridge safety and provide a precaution alarm. The traffic safety is ensured and the secondary damage caused by the broken bridge can be avoided. Moreover, the lifetime of the bridge is also extended by strengthening and repair taken in time. Furthermore, by long-term record of monitor data, a complete database of the bridge pier scour is established for pier protection and riverbed restoration in the future.
Among a lot of technologies that monitor the bridge pier scour, the most common methods are followings:
Ground Penetrating Radar: is a non-destructive method that uses electromagnetic radiation in the high frequency band of the radio spectrum, and detects the reflected signals from subsurface structures. Thus the elevation changes of the riverbed under the water are obtained. The advantage of this method is that the changes in the riverbed elevation can be recorded continuously yet the shortcoming is that the operation is time-consuming. Moreover, people need to take training classes for operation of the device.
Numbered Bricks: a brick array formed by bricks with fixed size and sequential numbers is mounted under the riverbed at the upstream around a bridge pier. When a flood comes, the riverbed elevation change is measured by the positions and numbers of the bricks swept away. The disadvantage of the method is that it requires to dig in the riverbed for mounting the brick array and each set of array can be used only once. Moreover, only the scour depth is learned while the sediment deposition is unable to detect.
Sliding Magnetic Collar: a slide bar with a hollow design is disposed on the surface of a bridge pier and a collar sleeve covers the slide bar. When the flood scours, the collar sleeve moves downward to provide the scour depth of a specific position. A magnetic sensor disposed in the slide bar moves along with the collar sleeve and sends movement signals to externals by wires. The disadvantage of this method is that it only records the scour depth but the sediment deposition is unable to detect.
The monitor methods available now all have certain limitations. Thus some other monitor systems have been developed. Refer to Taiwanese Pat. App. No. 91130327 and No. 93132366, an on-site monitor unit and a remote monitor unit are revealed. The on-site monitor unit includes a water tight tube that is set at the bridge pier under the water. An image capture device is disposed in the water tight tube so as to get images under the water and the images obtained are transmitted to the remote monitor unit for people to observe and learn the riverside elevation under the water. Thus the changes in the riverbed elevation are learned. Moreover, according to the riverbed elevation changes, people responsible for monitoring can send commands from the remote monitor unit to the on-site monitor unit so as to control the image capture device moving upward/downward and adjusting the image-capture positions. However, the monitor system transmits images with large data amount to the remote monitor unit for people to observe and check the riverbed elevation. The image transmission requires higher bandwidth consumption and the monitor system needs sufficient bandwidth. Besides, people got to monitor the images from the on-site monitor unit at all times so as to send commands for adjustment of the image capture device. This not only consumes labor and cost but also causes inconvenience in use.
Thus there is a need to develop a monitor system for monitoring riverbed elevation changes at bridge piers that overcomes above shortcomings. In the present invention, only the elevation changes of the riverbed are transmitted to a remote monitor unit so that the bandwidth consumption is reduced effectively. The problem of conventional monitor systems that requires higher bandwidth is solved. Moreover, the positions of the photographic unit are adjusted automatically by the monitor system of the present invention according to elevation changes of the riverbed. There is no need to operate the photographic unit by staffs responsible for monitoring. Thus the convenience in use is improved and the shortcomings of conventional techniques mentioned above have been overcome.